[doc] fix: fix typo in agentic RL documentation

[kibitzing]

What does this PR do?

Fix a typo in agentic RL documentation.

• current
  bash examples/data_preprocess/gsm8k_tool_agent_loop.py

• fixed
  python examples/data_preprocess/gsm8k_tool_agent_loop.py

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[gemini-code-assist]

Code Review

This pull request corrects a command in the agentic RL documentation. The change replaces bash with python for executing a Python script, which is the correct interpreter. This is a necessary fix for the documentation's accuracy. The change is correct and I have no further suggestions.